In known distributor-injection devices, the rotary pump which constantly fills the interior of the housing with fuel is embodied as a vane cell pump. An opening which connects the compression recess of the pump with the housing interior penetrates a receiving ring and a support ring in the axial direction and is disposed approximately in the center of the compression recess. Cavitation has been found in such devices particularly after long periods of operation, which can be traced back to the occurrence of underpressure.
As is shown on a chart of "Bosch Distributor-Type Fuel Injection Pump VA" (training chart VDT-U 2/304 En), copyright 1971, a roller ring is a supporting element of the rollers which bring about, among other things, the axial motion of the distributor piston in interaction with a cam plate. As explained in the description in the specification of the application, cavitation damages were noted in the area of the only axially directioned rupture in known injection devices which can be certainly traced to cavitation. This is explained in that the roller ring impacted or attacked by the pressure liquid starts to vibrate and this vibration causes the cavitation damages in conjunction with the pressure liquid in the inner chamber.